Oil-base drilling fluids



Patented Sept. 30, 1952 UNITEZD' STATES PATENT cmce v oir-nAssfift i rfliicrLums Union Oil Company of California, Los Angeles, l Calif., a corporation of California. i

No Drawing.

In drilling oilor gas'well-s' by means of rotary drilling tools, a hollow drill pipe known as a drill stem having a bit attached to its lower end is ex tended downwardly through the well bore and rotated while thebi-t is pressed against the working face in the formation at the bottom of the hole. The action of the rotating bit grinds away the formation as the drilling progresses. During the drilling, a fluid body known asa drilling fluid or mud is continuouslycirculated downwardly through the drill stem, through the bit and against the working face ofthe hole, and then upwardly through the annular space between the drill stem and the wall of the bore hole. The drilling fluid serves a number of purposes, among which are cooling and lubricating the drill bit, suspending" and removing cuttings from the bore hole, preventing the flow or liquids from the formations traversed by-the boreinto the same by. applying hydrostatic pressure to such for-mations, andfulfllling other purposes.

In locations where the underground formations traversed and/or penetrated by the bore contain materials such as hydratablecl'ays which swell and/or disintegrate in the presence of water, it has become customary to employ drilling fluids which are substantially free of water in order'to precede the introduction of water into the bore byjmeans of the drilling fluid. ,Such drilling fluids are termed oil-base? fluids since they usually comprise a mineral oil "having dispersed or suspended therein minor proportions of various agents adaptedto impart special properties to the composition. Among suchagents, the most universally employed are: we'ighting agents,- whicli are high density inertsolid's adapted to increasethe apparent densityof the base oil and thus" increase the hydrostatic head provided by the drilling fluid within the bore; wall-buildin agents, which are materials'such as clay or asphalt adapted to coat or plaster the walls of the bore with an impermeable layer which preventsthe escape of the drilling fluid into permeable formations; and dispersing agents which serve to maintain solid components of the fluid uniformly dispersed therein. Oil-base drilling fluids may also comprise a varietyof other agents such as gel strength improvement agents, viscosity modifiers, emulsifying agents, protective colloids, in-

organicsalts, etc. 7

pers-ible in fresh water.

ApplicationFebruary 19,1951, Serial No. 211,797 r y" 10 Claims. (Cl. 252-) the bore, if such fluid is employed in drilling into the producing formation there is considerable danger of plugging the poresv of such formation with gel-like particles of hydrated clay, thereby shutting off or impeding the flow of oil or gas.

Accordinglyflt has become common practice in some localities to drill down to the producing formation with a water-base fluid, and then to replace such fluid with an oil base fluid for completion of the bore into the producing formation.

In my co-pen'ding application, Serial No.

105,067, filed July is, 1949, now s. Patent No.

2,542,020; there are described and claimed oilbase drilling fluids] prepared by dispersing in mineral oil minor amountseachof an alkalimetal' alkali" partial saponification product of heat-treated rosin, such as the partial potassium soap of decarboxylate'd rosin; an alkalineearth metal base, such as calcium hydroxide; a hydratable' clay, such as bentonite; and water. The alkaline-earth metal base reacts by metathesis with the saponified rosin product to form the corresponding alkaline-earth metal rosin soap which serves at least in part as an oildispersible dispersing agent. The drilling fluids so prepared have highly desirable properties, and have met with considerable commercial success. However, they are not well suited for use in the presence of relatively large amounts of water and hydratable clay. Most types of naturally occurring hydratable clays are sodium-base clays which, in the hydrated form, are readily dis However, sodium-base clays react by metathesis with alkaline-earth metal bases in the presence of .water toform the corresponding alkaline-earth metal-base clays which are substantially non-dispersible in water andyor-oiln Accordingly, since the above described type 'of drillin fluid almost invariably contains some free un-metathesized alkalineearth metal base ,aswell as an alkaline-earth metal soap, .whensuch fluidis employed-in the presenceofsufficient water and a hydratableclay.

3 the latter reacts with the alkaline-earth metal base and/or soap to form the corresponding alkaline-earth metal-base clay. As previously stated, such clay is not normally dispersible in water and/or oil systems, and even though in the present instance a soap-type dispersing agent is present in thedrilling fluidysuch agent is not.

capable of dispersingthe' alkaline-earth metal base clay in the fluid to form a uniform composition. vAs a consequence, when a drilling fluid of the present type comes in contactwith a hy- .dratable clay in the presence of sufiicient water;

the clay is changed by chemical reaction-into a 4 herein will occur to those skilled in the art upon employment of the invention in practice.

I have now found that the above and related objects may be realized by providing in the oilbase fluid a small but effective amount of a particular type of non-ionic surface active agent' capable of maintaining alkaline-earth metal-base clays substantially uniformly .dispersed in the fluid. More particularly, I have found that certain hydroxypolyoxyethylene ethers of long chain fatty acid partial esters of .sorbitan are capable of dispersing alkaline-earth metal-base clays in non-dispersible form which settles out of the;

fluid in the form of a heavy sludge. In someinstances, such sludge is comprised of relatively small particles of non-dispersed clay. In other cases, the clay agglomerates into balls or clumps which may be as large asseveral inches in diam.-

eter, and may completely fill the body of the fluid. In either case, the non-dispersed clay sludge seriously interfere with the-drilling operation by cloggiing the shaker screens, filling up the mud ditches and settling pits, rendering pumping ofthe fluid 'very difficult if not imposhydratable clay in the presence of a substantial quantity of water. However, such conditions may 7 occur. in several ways, and are by no means rare. I Forfexample, the oil-base drilling fluid may become contaminated with water either as a result of water enteringthe hole from water-bearing form'ations traversed by the. bore or as a result of surface water getting into the mud ditches,

settling 'pits,.etc. When the drilling fluid becomes contaminated with water to an extent of about per cent or greater, and thereafter comes in c'on'tactjwith a hydratable clay, for example a sub s'urface clay-bearing formation, the abovedescribed sludge formation and attendant difliculties occur. Sludge formation also occurs When the oil-base fluid is usedto replace a Water-base fluid in the previously-described type of completion practice, since a substantial quantity of the aqueous hydrated clay water-base fluid invariably becomesadmixed with the oil-base completion fluid. Sludge formation similarly ocours in other instanceswherein clay and a substantial quantity of water become admixed with an alkaline-earth metal base-containing drilling fluid. t

It is accordingly an object of the present invention to providemeans for preventing theac- 'cumulation of clay sludge in oil-base drilling fluids of the aforesaid type.

Another object is to provide means for treating water-contaminated oil-base drilling fluids.

of the aforesaid type so as to prevent the accumulation of clay sludge whenthe water-contaminated fluid subsequently comes in contact with a hydratable clay.

A further object is to provide oil-base drilling fluids especially adapted for use in completion practice carried out subsequent to drilling operations in which a water-base drilling fluid has been employed. 1

.Otherobjects will :be apparent from the following detailed description of theinvention, and various advantages not specifically referred to discontinued and the oil-base drilling fluids in the presence of waterand hydratable clay are overcome, and the field oil-base drilling fluids of the present type. Accordingly, by incorporating into the fluid 'a relatively small amount-of such surface active agent, the aforementioned 'difliculties associated with the use of alkaline-earth metal base-containing of use of this type of drilling fluid is greatly extended. The surface active agent maintains the alkaline-earth. metal-base clay which is formed under such circumstances uniformly suspended in the fluid, and prevents it from accumulating in the fluid in the form of a heavy sludge or agglomerated balls or clumps.- Also, the particular surface active agentsemployed do not in any way,

detract from the desirable physical properties of the fluid, and the excellent viscosity,:fluid loss and gel strength characteristics of this type of.

fluid are retained to their fullest extent,

The invention thusconsists in improved drilling fluid compositions prepared by dispersing inf. 1

mineral oil a minor proportion each of an alkali metal alkali partial saponification product of, heat-treated rosin of the type hereinafter morefully described, an alkaline-earth metal base, a

hydratable clay, a hydroxypolyoxyethyleneether of a long chain fatty acid partial ester of s0rbit an,. and water. These compositions are complex col-H loidal systems whose exact chemical composition is made uncertain by the fact that certain of: the

components react with each other to an unknown extent. Accordingly, these compositions are herein described and claimed by their method of preparation rather than in termsoftheir chem ical composition which at best can be only sp'ecu lative. COMPONENTS The base oil which forms a major component of thenew drilling fluid compositions is pref-5" erably of mineral origin and may be crude. petroleum Or a distillate or residuum material.

Heavier .materials such as light tars, cracked residua, heavy extracts and thelike are especially well'suited,.particularly when blended. with a light distillate such as gas oil, diesel fuel, etc. a A

highly satisfactory mixed base of this type comprises amajor proportion, e. g., 60-95 per cent, of a relatively heavy oil such as a light residual oil having a specific gravity of about 13-15 API.

and a viscosity of about 30-40 seconds SSE at 1221F. and containing. substantial amounts of. asphaltenes, polymeric bodies and the like, and

a minor proportion, e. g., 5-40 per cent, of a light distillate such as .a dieselifuel having a specific gravity of about 25-35. API and a viscosity-of about 30-50'SUS at F. The invention, how

ever, isnot limited to the use of any particular typeof oilor mixtures thereof, and any of the oil bases known in the art may be satisfactorily employed.

The saponified rosin "product which is provided -1n the new compositions for the primarypurpose 5v of; maintaini lnsoluble. .comiionents uni.- formly; andstably dispersedin the oilphase-is the nroductobtain d y reacting: wood r umrosin which has previously been heat-treated to modify theiresinacids with an alkali-metal alkali, .e, g., sodium drox d di m ar o a potassium. hydroxide. et 1 such m ner thatthe sapO fiati n; r a i n s only p a ly. omp e e an t saponified product contains from aboutltoabout 1;5 per cent of free unsaponified resin acids. The eat-treatment of o in whereby. he sin. ac ds hereof re som zed and/ r e w se odified.

s-wellknown in he av lstores a t. nd m yb efiectedin va ious w ysto obt in modified rosi roducts which. a somew at. n hei p ysi al and emica p op r es ene di e upon. h atur and extent. of th eata m Thu o he 110 152 191 rad s f efin d woo reumrosin may b heated nder. n nxid zin on ns at emperatur s b e n ab t 2.50 C- an bo t iuo? c. ior a length time f ci nt o ra s the pecific ota on o he o inr m ts under such conditionsdecarboxylation takes'place with the formation of unsaponifiable bodies.- which are usually referred to as rosin fIheheat-treatment of rosin to. secure the des red modification of the resin acids as indicatediby increase. in specific rotation to a value aboyaabout +59 may alsobe effected in the presence-of catalysts at relatively low temperatures as describedin .U. S Patent No. 2,154,629. The catalysts employedare of the hydrogenation type, 84s.; metallic platinum orpalladiuin, although theftreatment is carried out in the absence of added hydrogen. The reactionwhich. takes. place is jtermed disproportionation since it involves the. simultaneous, hydrogenation and. dehydror genationj of abietic-type acids with the conse quentjformation of dihydroabietic and dehydroabietic acids and their analogues, and the resultingl'productis referred to as disproportionate'd' csin. Similarly, the product obtained by heat-treating, rosin under conditions sufficiently drasticj, that carboxyl groupsareremoved from the rosin acids is termed decarboxylatedrosin," and th'eproduct. obtained by, heat-treating rosin underfless drastic conditions so that the change effected issubstantially only one of molecular rear h gen'ient is referred to. as isomerized rosin. Alllof thesemodified rosin products are characteriaed by, having beenprepared by" heat-treating rosinunder conditions of time and temperatura and in the presence or absence of a hydrogenation catalyst but in the absence. of added by rogen, sufiicient to raise the specific rotation of; the rosinto a value above about Any of the above described modifiedrosinproducts maybe used to obtain the saponification educts em oyed ena inethe d i ing fl i compositions of thepresent invention. Procedure fo g carrying out; the saponiii-cation reaction; is

.well kngwn in; the art, and in general consists...

met-sly addi g th mod fied rosin in :the; solid 6; or moltenstate to. ahotaqueous solution of the desired: alkali-metal alkali and thereafter heating. the mixture until the reaction is complete. and the product containsthe desired amount of water. The amount of alkali employed is somewhat less than that required for the complete saponificar tion of, the, resin acids in order that thetsaponifiey cation product may contain the requisite amount of; freeunsaponified resin acids. The concentration of the aqueous alkali is usually so. adjusted that, the product obtained takes, the form. of; a viscous liquidror; thick paste containing 60-85. per centasolids The. physical form of the product also dependsysomewhatpupon the typenof modified rosin employed. The saponification product obtained fromnecarboxylated wood rosin containing a substantial amount of rosin oils, for example, is a relatively fluid liquideven though it may contain only 5.-10.p er cent of. water.

Whileany of the alkali-metal alkali saponification products of resin which has been heatetreat ed to raise its: specific rotation to a value above about 5 may be employed in preparing the present drilling fluids, I have found that superior results, particularlywith respect to the fluid loss value of the, drilling fluid: are attained by employing eitherof two specific products of, thistype.

uct oflrosin which has been heat-treated at temperatures between about 250 C. and about 350 C.

in theabsence-of a catalyst to suchan extent that.

it contains only about 50,-6.0percent of free resin acids, 30,-4Q;per cent of unsaponifiableoils, and smallamountsof phenolic materials, water, and

heat-treated rosin containing about: 45-55 per.

cent potassium resin acidsoaps, about 30-35 per cent unsaponifiablematerials, about 5-10 per cent, free; resin acids, and about 5- 10 per cent water. The second of the. preferred. class of saponification products'is the; product obtained by heating; rosin at. a temperature of" about 225-300?- C. for about 15-60 minutes in contact with a palladium catalyst, distilling the resulting product; and-collecting a .fraction distillingat about 2IO.-275 C. under about 5-10'mm. pres-- sure, and, thereafter, saponifying such fraction with aqueous sodium; hydroxide in the known manner. Such product is-available commercially under the trade-name ,Dresinate 731.

The alkaline-earthmetal base employed-inprew paring the new drilling fluids may ,be i any oxide, hydroxide or basic salt of any of the alkaline earth metals, e. g., calcium oxide, calcium hydroxide, barium hydroxide, strontium hydroxide, calcium acetate, etc. Calcium hydroxide, e. g., ordinary hydrated lime, and calcium oxide are preferred for reasons of low cost and. general availability.

The hydratable clay component is preferably ahigh quality material; such as bentonite, montmorillonite, or kaolinite, but may be common clay such asis available in almost any locality;

olyoxyethylene ethers of long chain :fatty acid.

thereof. ployed should be such that the ether product conpartial esters of sorbitan.- Such agents are available commercially under the generic trade name Tween. They are prepared from sorbitol by the following series of operations:

1." Esterification of-one-or more, but not all, of th'e'hydroxyl groups of sorbitol molecule with a longchain fatty acid, e. g., oleic acid, stearic acid, palmiticacid,-lauric acid, and other fatty acids containing at least 12 group or groups of said partial ester with ethylene oxide to form ahydroxypolyoxyethylene ether The quantity of ethylene oxide emtains from to oxyethylene groups. I

Means for carrying out these reactions are well known in the art, and further details concerning the preparation of the products in question are set'forth'in' that portio'n of U. S. Patent'No. 2,380,166 which relates to the preparation of the so-called Type Bzemulsifiers. These products are for the most part oily yellow liquids which are soluble in water, acetone, alcohol and other common organic solvents. They vary in viscosity from about 250 to about 600 cps. at 25 C., depending upon the nature of the long chain fatty acid residue, the number of such residues 'in the molecule, and the length of the hydroxypolyoxyethylene chains. As examples of 'the'surface active agentsof the present group these may be mentioned hydroxypolyoxyethylene so r bi t a n monolaurate, hydroxypolyoxyethylene sorbitan monopalmitate, hydroxypolyoxyethylene sorbitan mono-oleate, hydroxypolyoxyethylene' sorbitan tri-oleate, etc. While any of such products may be employed in preparing the drillingfluid compositions of the present invention, best results are attained through the use of those products which havea hydrophile-lipophile balance value (abbreviated HLB value) above about 12. The HLB value is an emperical numerical value which expresses thejrelative hydrophilic and lipophilic properties 'of the product under consideratmn. A high HLBvalue is indicative of strong hydrophilic properties, whereas a low HLB value indicates-strong lipophilic properties. The products which have HLB values above about 12 and which are preferred for use according to the present invention are highly hydrophilic. "A particularly preferredmaterial i the hydroxypoly oxyethylene sorbitan monolaurate product having an HLB value of about 16.7, which is sold under'. the trade name Tween 20. Further information concerning these materials and their HLB values is set forth in Atlas' Surface Active Agents, Atlas Powder Company, Wilmington, Delaware, 1950. j

PROPORTIONS, j

The proportions in which the'variouspessential components are employed may be'varied between certain limits depending upon the identity of such components and the specific properties desired in the composition. Ordinarily, however,

the saponified heat-treated rosin product i em-" ployed in an amount representing' between about 1 and about 10, preferably between about 4 and about 8, per cent by weight of the entire composition. The alkaline-earth metal base is em-' ployed inan amount corresponding approximate 1y to that chemically equivalent to thesaponified rosin product. .When thelatter is one of the preferred products, hereinabove described and the alkaline-earth metal base is calcium oxideor hycarbon atoms, to form a sorbitan partial ester. I I

-2. Etherification of the remaining hydroxyl' droxide, the saponification product is provided in the above-mentioned amount and the base isemployed in an amount representing between about: 0.1 and about 5, preferably between about 0.4and about 2, per cent by weight of the entire composi tion. The hydratable clay is employed in -an: amount representing between about 0.1 and-about '5, preferably between about 0.4 and about 1.2, per cent by weight of the entire composition, and

the water is provided in an amount representing between about 0.2 and about 10, preferably be-*' tween about 1 and about 5, per cent by weight of the entire composition; These proportions of water include any water which may be contained.

in the saponified rosin product and/or other'comp nents, and accordingly" the amount'of water actually added during preparation of the com-" position will be adjusted according to the water content of the other components so that the final composition will contain water in the above mem tioned proportions. The hydroxypolyoxyethylen'e' ether surface active agentis employed in an amount representing between about 0.05 and: about 2, preferably between about 0.1and about 1, per cent by weight of the entire composition.'-

PROCEDURE The exact manner in which the various com;

ponents are dispersed in the base oil is notof, primary importance, and if desired the requisite amount of each may simply be added to themtire quantity of the base oil at ordinary temperaj tures while employing more or less vigorous agife tation or stirring to secure'a uniform composietion. Such operation may be carried out at the well site in the conventional mud pit jwith ag'i-"j tation being effected by circulating themixture'l" from one pit to another. However, it is often; more convenient to preparean initial concentrate composition which can subsequently be diluted with the base oil to obtain the finished'drilling fluid. Thus, the saponification product, alkaline f earth metal base, clay, water and surface 'actiye agent may be dispersed in a portionof the base oil to form a relatively thick viscous compositionj which can be stored and shipped in drums, and

subsequentlybe diluted withthe remainder of the base oil to obtainthe finished product. When the j base oil comprises a mixture of a light anda heavy oil, it is preferred that the light oil be'em ployed in forming the initial dispersion. Accord-f ing to one mode of procedure, the alkaline-earth":

metal base is suspended in a portion of the'basej line-earth metal base being added along with thef remainder of the base oil at some later time? Weighting agents, gel strength agents andother optional components are usually added along with or subsequent to dilution of the concentrate to form the finished product.

Usually) h drilling fluid compositions of th invention will be' prepared by combining the'in dividual components; thereof as just -described'fl However, they may also be obtained by "siiitalily modifying previously prepared composition-s arx the proper type. Thus, any of the drilling fluid'sl- I to an oil-base fluid which has become contaminatedwith a water-base fluid is illustrated by the data set forth in Table II, below. A mixture of water-base and oil-base fluids correspondingfto Sample No. 6, above, was prepared and divided into a number of samples.

Each sample was "stirred for about 100 minutes, after which its physical appearance was noted. Tn each sample there was thenadded the indicated quantity of the dispersing agent, and after stirring for minutes at about 160 C. the physical appearance was'again noted. The observations are tabulated -as follows Table II Dispersing Agent Appearance after Appearance after ,Adding Dispers- Sample No. Stirring for 100 ing Agent andS tirring 20 Min. Mm. Identity 1:53?? at 160 0..

Solid sludge Carboxymethyl-cellnlosc 0.2 Heavy sludge separation amountp. v U 5 V l ing to 55% by volume. v do sorbitan monolaurate. 0.1 Heavy sludge separationamounting to 65%by volume.

do Bentonite 6.0 Heavy sludge separation amounting to 75% by volume. do Heiradecylamine 0.2 Heavy sludge separation amount- 1 ing to 60% by volume.

do Saponified disproportionated 0.2 Heavy sludge separation amountrosin. ing to by volume.

do Sodium silicate 0. 4 Heavy sludge separation amountf ing to% byvolume. do sorbitan monopalmitate.i OJI Heavy isludge "separation amount- Y ing to by volume. do sorbitan monostearate 0.1 Do.

i sorbitan mono-oleate 0..1 Do. d Hydroxypolyoxyethylene sorbi- 0. 2 Uniform fine grainy fluid.

tag monolaurate (Tween 20). 0 1 D o 0.

data were obtained by adding varying amounts of a typical water-base fluid, which comprised 565 parts of Rogers Lake clay dispersed in 1500 parts of water, to separate samples, of an oil-base fluid which had been prepared by dispersing minor amounts each of the previously described sodium hydroxide saponification product of distilled disproportionated rosin, hydrated lime, clay and water in a base oil consisting of a mixture of a light diesel fuel and a light fuel oil as hereinbefore described. Finely-divided whiting was added as a weighting agent, and each sample of mixed waterand oil-base fluid was stirred for 100 minutes at room temperature and for 20 minutes at 160 F. to simulate drilling conditions. The samples were then examined for sludge formation. The following results were observed:

Samples Nos. 7 and 8 were entirely too thick to be circulated. It will be noted that the aforemen-' tioned sludge formation occurs when the waterbase fluid contamination becomes greater than about 15 per cent.

The effect of adding various dispersing agents It will be noted that of the various dispersing agents tested only the hydroxypolyoxyethylene- EXAMPLE 1 Approximately 3350 parts of Dresinate 731, Z00 parts of water, and 1100 parts of bentonite are dispersed in a mixed base oil comprising 2350 parts of light diesel fuel and 1400 parts of light fuel oil. The light diesel fuel is a. typical 400- 720 F. boiling range petroleum fraction, and has an API gravity of about 31 and a viscosity of about 40 SUS at F. The fuel oil is a heavier fraction having an API gravity of about and a viscosity of about 36 SSE at 122 F. Approximately 1800 parts of the resulting concentrate composition are then diluted with about 16,500 parts of the fuel oil, and there is then added about 38 parts of hydrated lime. The resulting mixture is stirred for about hour, whereby the lime and sodium soap react by metathesis to form the corresponding calcium soap. About 55 parts of hydroxypolyoxyethylene sorbitan monopalmitate having an HLB value of about 15.6 (Tween 80) are then stirred into the composition and the product is stored until ready for use. This oil-base drilling fluid is resistant to sludge formation even when contaminated with asmuch as 30 per cent of water and clay.

"The saponified decarboxylated rosin product is the potassium hydroxide saponification product of decarboxylatedrosin obtained by heating wood rosin at about 280-320 C. for 2-4 hours. It is a dark-colored highly viscous fluid comprising about 50 per cent of the -.potassium soaps of modified rosin acids, about 7 per cent of un saponified rosin acids, about 33 per cent of unsa'ponifiable rosin oils and about 10 per 'cent' of water. The mixing procedure is the same as that employed in Example I.

7 EXAMPLE III Per cent by v weight Crude petroleum 84.5 Sodium soap of disproportionated rosin 3.0 Potassium soap of decarboxylated rosin .2.0 Bentonite 5.0 Water 2.5' Hydrated lime 1.0 Hydroxypolyoxyethylene sorbitan monolaurate 2.0

EXAMPLE 1v 7 Per cent by weight Light mineral oil (22 API) 79.7 Sodiumsoap ofdisproportionated rosin, 6.3 Bentonite 5.0 Water 5.5 Hydrated lime 2.5 Hydroxypolyoxyethylene sorbitan monostearate 1.0

This composition is weighted to an apparent density of 120 lbs.'/cu. ft. by the addition of 200- mesh whiting. Barytes, iron oxide, fullers earth and other conventional weighting agents may be substituted for the whiting.

"Other modes or applying the principle of my invention may-be employed instead of 'thoseex- 12 by weight of free rosin acids; between'about 0.1 and about 5 per cent by weight of a hydratable clay; an alkaline-earth metal .base in an-amount corresponding approximately to that chemically equivalent to the quantity of said saponified rosin product present; between about 0.2 and about 10 per cent by weight of water; and between about 0.05 and about 2 percent by weight of a hydroxypolyoxyethylene ether of a long chain fatty'acid artial ester of sorbitan.

2. A composition as defined by'claim 1-wherei'n the' saponified rosin product is a potassiumhye droxide saponification product of Wood rosin which has been heated at a temperature between about 250 C. and about 350 C. .for' a period of time sufiicient to raise its specific rotation to a value above about {5, and comprises between about 45 and about 55 per cent of potassium resin acid soaps, between about and about per cent of unsaponifiable materials, between about 5 and about 10 per cent of free resin acids, and between about 5 and about 10 per cent of water.

3. A composition as defined by claim 1 wherein the saponified rosin product is a sodium hydroxide saponification product of distilled disproportionated rosin.

4. A composition as defined by claim 1 wherein the alkaline-earth metal base is selected from the class consisting of calcium oxide and calcium the hydroxypolyoxyethylene ether of a long chain product obtained by saponifying with an aqueous alkali-metal alkali rosin which has been heat-treated at a, temperature between about 250 C. and about 350 C. for a period of time sufi'icient to raise its specific rotation to a value above about +5; said saponified rosin product containing between about l'and about 15 per cent fatty acid partial ester of sorbitan is one containingfroni 10 to 30 oxyethylene groups.

6. A composition as defined by claim 1 wherein thehydroxypolyoxyethylene ether of a long chain fatty acid partial ester of sorbitan is hydroxypolyoxyethylenesorbitan monolaur'ate having a hydrophile-lipophile balance value of about 16.7.

7. A drilling fluid composition prepared bydis persing in mineral oil between about 4 and about 8 per cent by weight of a saponified rosin'product selected from the class consisting of (1) a potassium hydroxide saponification product of wood rosin which has been heated at atemperature between about 2.50 C.'and about 350 C. for a period of'timef suflicient to raise its specific rotation toavalue above about i-5,.said saponified rosin'product comprising between about and about per cent of potassium resin acid soaps, between about Y30 and about 35 per cent of unsaponifiable materials, between about 5 and about 10 per cent of free resin acids, and between about 5 and about 10 per cent of water, (2) a sodium hydroxide saponification product of distilled disproportionated rosin, and .(3) mixtures of (1) and (2) between about 0.4 and about 1.2 per cent by weight of a hydratable clay; between about 0.1 and about 5 per cent by weight of an alkalineearth metalbase; between about 2 and about 5 per cent by weight of water; and between about t 0.1 and about 1 per cent by weight of a hydroxypolyoxyethylene ether of a long chain fatty acid ester of sorbitan.

8. A composition as defined by claim 7 wherein t the alkaline earth metal base is selected from the class consisting of calciumoxide and calcium 10. ,A composition as defined-by clainr'l where in the hydroxypolyoxyethylene etherof a long 13 chain fatty acid partial ester of sorbitan is hydroxypolyoxyethylene sorbitan monolaurate having a hydrophile-lipophile balance value of about 16.7.

PAUL W. FISCHER.

REFERENCES CITED The following references are of record in the file of this patent:

A 14 UNITED STATES PATENTS Number Name Date 2,463,823 Weitkamp Mar. 8, 1949 2,542,019 Fischer Feb, 120, 1951 2,542,020 Fischer Feb. 20, 1951 OTHER REFERENCES Atlas Surface Active Agents" by Atlas Powder (30., p. 8 (1948). 

1. A DRILLING FLUID COMPOSITION PREPARED BY DISPERSING IN MINERAL OIL BETWEEN ABOUT 1 AND ABOUT 10 PER CENT BY WEIGHT OF SAPONIFIED ROSIN PRODUCT OBTAINED BY SAPONIFYING WITH AN AQUEOUS ALKALI-METAL ALKALI ROSIN WHICH HAS BEEN HEAT-TREATED AT A TEMPERATURE BETWEEN ABOUT 250* C. AND ABOUT 350* C. FOR A PERIOD OF TIME SUFFICIENT TO RAISE ITS SPECIFIC ROTATION TO A VALUE ABOVE ABOUT &5* , SAID SAPONFLED ROSIN PRODUCT CONTAINING BETWEEN ABOUT 1 AND ABOUT 15 PER CENT BY WEIGHT OF FREE ROSIN ACIDS; BETWEEN ABOUT 0.1 AND ABOUT 5 PER CENT BY WEIGHT OF A HYDRATABLE CLAY; AN ALKALINE-EARTH METAL BASE IN AN AMOUNT CORRESPONDING APPROXIMATELY TO THAT CHEMICALLY EQUIVALENT TO THE QUANTITY OF SAID SAPONIFLED ROSIN PRODUCT PRESENT; BETWEEN ABOUT 0.2 AND ABOUT 10 PER CENT BY WEIGHT OF WATER; AND BETWEEN ABOUT 0.05 AND ABOUT 2 PER CENT BY WEIGHT OF A HYDROXYPOLYOXETHYLENE ETHER OF A LONG CHAIN FATTY ACID PARTIAL ESTER OF SORBITAN. 